Images and rotation angles
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Hola,
I have a theoretical question as I'm looking for ideas how to solve my current image analysis problem (a field which I am not an expert).
The problem is: I have 40 images of different types of drinking bottles in various rotation angles. Therefore, I am looking for a way how to automate the rotation process so all of them will have the same angle (neck up, base down), any idea how to solve it?
Thank you.
采纳的回答
Image Analyst
2013-4-20
0 个投票
See my image segmentation tutorial. http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862
Basically you first need to find the bottle, by thresholding or whatever. Then you need to run regionprops and look for the orientation - that will tell you the angle - and the Centroid and MajorAxisLength. It will fit an ellipse to the bottle. Look at the location of the midpoint of the MajorAxis. It will be closer to one end (thick or thin - I'm not sure) of the bottle than the Centroid will be. So, knowing that you'll be able to rotate it so the thick end is down.
Please upload some of your images, including the binary images showing the detected bottle mask.
4 个评论
Lluis Roca
2013-4-22
Image Analyst
2013-4-22
What I'd probably do it to call regionprops() and find the orientation (angle).
measurements = regionprops(binaryImage, 'Orientation');
angle = measurements(1).Orientation;
angleToRotateBy = 90 - angle; % or "+" or 180 (instead of 90), you'd have to check.
Then use that in imrotate to rotate the image.
rotatedImage = imrotate(rotatedImage, angleToRotateBy);
After it's been rotated, I'd sum horizontally
verticalProfile = sum(rotatedImage, 2);
and look at the first 50 non-zero sums at the top and the bottom.
firstLine = find(verticalProfile > 0, 1, 'first');
lastLine = find(verticalProfile > 0, 1, 'last');
topSum = sum(verticalProfile(firstLine:firstLine+50));
bottomSum = sum(verticalProfile(lastLine-50:lastLine));
If the topSum is greater than bottomSum, it's upside down and needs to be rotated 180
if topSum > bottomSum
rotatedImage = imrotate(rotatedImage, 180);
end
Lluis Roca
2013-4-25
Alex Taylor
2013-4-25
Lluis,
Anyway you can post a few of the original, non-segmented images that you are interested in?
Thanks,
Alex.
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Anand
2013-4-21
Another option is to register the images using imregister. If you know that the only deformation between the images is the rotation, you can use the 'rigid' transformation type. If there is a scale change involved, you should use the 'similarity' transformation type.
Here's a small example of how to use this:
% read in a test image
im = imread('cameraman.tif');
% rotate it to create another test image
imRot = imrotate(im,45);
figure; imshowpair(im,imRot,'montage');title('before registration');
% setup intensity-based image registration
[optimizer,metric] = imregconfig('monomodal');
% register imRot with im so that cameraman is upright
imReg = imregister(imRot, im, 'rigid', optimizer, metric);
figure; imshowpair(im,imReg,'montage');title('after registration');
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2013-4-20
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